80 head on an 81?

[bpw]

Would this work? I know there was achange to nikasil in 81 and more power but does anyone know if the older head would fit?   I assume you would need to change both at the same time.

Thanks
Ben

[Rob Valdez 79 R65]

I don't know.  I was wondering this same thing earlier after reading of your plight.
The reason is, I sold a couple of heads (one '79 and one '80) to a breaker several years ago.
A matching (2nd gen.) head should not be hard to scare up.  

[bpw]

Well after some research:
Bike Bandit lists both with the same part number but other microfiches show a 9/80 on designation but no number for earlier versions.  Talking to BMW re-cycle he was pretty sure the only difference was the exhaust recyling piping for emmissions.  saw 1 site that said valves where bigger in later models but again part numbers only show one size available.  

Anyone know the size of their valves off hand?

Thanks
Ben

[NC Steve]

In '81 the valves were upped 2mm at both intake & exhaust.
I'd have to check The Book to see what they measured, but definitely larger than the '79,'80 models.

[bpw]

Ok just found that out actually, course the real question now is can I put the old ones on anyways and just live with a little less power until I find the correct ones, assuming a pair. Seems possible but hard to tell without trying.  Theres some 80's on ebay I think Ill get if they dont get too high and give it a shot.  If they dont work I can re-sell them.

ben

[NC Steve]

No clue if they'll fit, but Rob probably knows. You might want to email Ebay seller lamontsanfurd, aka Larry in Austin, who deals in lots of good used stuff and was recently parting out a later model R65, an '82 I believe, with low mileage.

Also, you might try our own Don Whiteside and Rev. Eddie, both of whom have (or had) very impressive R65 parts caches squirreled away!

Good luck! [smiley=thumbsup.gif]


Retroactive PS: See Rob's post below, and also try the "regular" http://www.ibmwr.org/market/ as another good source of parts.

[Rob Valdez 79 R65]

I am not sure about Don, but I think with Rev. Eddie, it is an on-going affair.

There are many used parts dealers.

A good friend of mine is Matt at Boxerworks.  He is in Georgia.  His phone # is (706) 310-0031.  I have no financial ties with Matt, just supporting the providers of a very cool forum.

Here local in Indiana, is Galen Perry (765) 564-6338  I am pretty sure he would have what you need.

Here is a pretty good link I found while searching for Galen's phone #:
http://www.ibmwr.org/otech/sources.html

I would stick to getting a '81-'84 head.  I am very confident that you could scare one up before the week is out.

[steve hawkins]

I think it is only one of the valves that is bigger on a post 81 head - can t remember which.  However it is worth 5 ponies....so you would definately be replacing the pair.  5 ponies is a 10% power drop.....

Also I think the rocker posts were different, or at least the way the posts were mounted onto the heads is.  I had to do some messing around when I went the other way.  I fitted the post 81 heads to a 79 engine and had to transfer all the rockers across.  It was no great shakes though.

Get yourself a tech drawings/microfiche and compare the two.

I was lucky, as I had a busted exhaust thread, a couple of broken fins on a pair of leaded heads that had done 94,000 miles - i.e. in definate need of a valve job!

I rang motorworks and they had a pair in stock that had new guides and unleaded valve seats - so instead of fixing mine I bought those.  The valves supplied needed laping in, but that took minutes.

Steve H

[Chris_in_BC]

I think it is only one of the valves that is bigger on a post 81 head - can t remember which.  However it is worth 5 ponies....

Both valves changed in '81

Up to 1980 - Inlet was 38mm , Exhaust was 34mm
In 1981 it was - Inlet was 40mm , Exhaust was 36mm